Group B Streptococcus type III (GBS) studies - We found that an experimental polysaccharide GBS Type III vaccine did not elicit an immune response in 10 rhesus monkeys (Macaca mulatta). This presents serious problems for proposed studies using this vaccine to immunize monkeys and probably humans to GBS type III. Cytomegalovirus: We were unable to infect chimpanzees (Pan troglodytes) with human cytomegalovirus AD-169. We found that in a colony of 70 chimpanzees, 10 were actively shedding a cytomegalovirus (CMV) that closely resembled simian CMV. All animals tested had preexisting antibody to CMV which cross-reacted with human AD-169 CMV. Herpes encephalitis: Herpes Simplex virus type I (HSV 1) produces encephalitis in rhesus (Macaca mulatta) and cynomologus (Macaca fascicularis) monkeys provided the animals are antibody negative for all herpes viruses. This gives us a model to study early diagnosis of herpes encephalitis. Varicella-like Delta Agent encephalitis: The Delta virus will produce encephalitis in young antibody negative patas monkeys (Erythrocebus patas). This model permits us to test new therapeutic agents for treatment of varicella encephalitis.